kernel: add support for mediatek NMBM flash mapping support

This NAND flash remapping method is used on newer MediaTek devices with NAND
flash.
Signed-off-by: NFelix Fietkau <nbd@nbd.name>

target/linux/generic/files/drivers/mtd/nand/mtk_bmt.c

@@ -392,6 +392,8 @@ int mtk_bmt_attach(struct mtd_info *mtd)
 
 	if (of_property_read_bool(np, "mediatek,bmt-v2"))
 		bmtd.ops = &mtk_bmt_v2_ops;
+	else if (of_property_read_bool(np, "mediatek,nmbm"))
+		bmtd.ops = &mtk_bmt_nmbm_ops;
 	else if (of_property_read_bool(np, "mediatek,bbt"))
 		bmtd.ops = &mtk_bmt_bbt_ops;
 	else
@@ -410,14 +412,14 @@ int mtk_bmt_attach(struct mtd_info *mtd)
 	bmtd.pg_shift = ffs(bmtd.pg_size) - 1;
 	bmtd.total_blks = mtd->size >> bmtd.blk_shift;
 
-	bmtd.data_buf = kzalloc(bmtd.pg_size, GFP_KERNEL);
+	bmtd.data_buf = kzalloc(bmtd.pg_size + bmtd.mtd->oobsize, GFP_KERNEL);
 	if (!bmtd.data_buf) {
 		pr_info("nand: FATAL ERR: allocate buffer failed!\n");
 		ret = -1;
 		goto error;
 	}
 
-	memset(bmtd.data_buf, 0xff, bmtd.pg_size);
+	memset(bmtd.data_buf, 0xff, bmtd.pg_size + bmtd.mtd->oobsize);
 
 	ret = bmtd.ops->init(np);
 	if (ret)

target/linux/generic/files/drivers/mtd/nand/mtk_bmt.h

@@ -23,6 +23,9 @@ struct mtk_bmt_ops {
 	int (*debug)(void *data, u64 val);
 };
 
+struct bbbt;
+struct nmbm_instance;
+
 struct bmt_desc {
 	struct mtd_info *mtd;
 	unsigned char *bbt_buf;
@@ -38,7 +41,10 @@ struct bmt_desc {
 
 	const struct mtk_bmt_ops *ops;
 
-	struct bbbt *bbt;
+	union {
+		struct bbbt *bbt;
+		struct nmbm_instance *ni;
+	};
 
 	struct dentry *debugfs_dir;
 
@@ -70,6 +76,7 @@ struct bmt_desc {
 extern struct bmt_desc bmtd;
 extern const struct mtk_bmt_ops mtk_bmt_v2_ops;
 extern const struct mtk_bmt_ops mtk_bmt_bbt_ops;
+extern const struct mtk_bmt_ops mtk_bmt_nmbm_ops;
 
 static inline u32 blk_pg(u16 block)
 {

target/linux/generic/hack-5.10/430-mtk-bmt-support.patch

@@ -17,7 +17,7 @@
  
  nandcore-objs := core.o bbt.o
  obj-$(CONFIG_MTD_NAND_CORE) += nandcore.o
-+obj-$(CONFIG_MTD_NAND_MTK_BMT)	+= mtk_bmt.o mtk_bmt_v2.o mtk_bmt_bbt.o
++obj-$(CONFIG_MTD_NAND_MTK_BMT)	+= mtk_bmt.o mtk_bmt_v2.o mtk_bmt_bbt.o mtk_bmt_nmbm.o
  
  obj-y	+= onenand/
  obj-y	+= raw/